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Monday, 27 February 2012

BPA and Endometriosis

One of the most troubling questions that still looms large over the heads of all of those affected by endometriosis is, where does the condition come from? More specifically, what causes endometriosis? We know that there are genetic factors that influence the risk of developing endo, so if your mother had the disease, you are more likely to have it, but if that is the case, where did your mother get it from? From her mother probably, but there has to be a point where it originated because there are many women who have no family history of endometriosis yet still develop the condition.

If we look at other complex conditions like cancer, for example, there are the familial risk factors but there are also external factors that influence the risk. For cancer there is, well, quite a lot of things really, the worst of these you can avoid simply by living a healthy lifestyle, but if you want to escape all potentially harmful substances you’ll have to seal yourself in a vacuum chamber and get buried 2000miles under the earth. So it is a reasonable question to ask whether there are any external factors that influence the development of endometriosis.

The first aspect we need to consider, when trying to answer this question, is the issue of timing of exposure. I’ve put a few posts on here that provide evidence suggesting endometriosis is something you are born with, therefore there is not much point in looking for influencing factors in grown women with well established disease. If endometriosis is indeed a condition you are born with, then exposure during the development of the foetus is probably the most important time to consider the influence of external factors.

Where do you start though when looking for potential environmental nasties? As we know endometriosis is an estrogen dependant disease, so it would make sense to look at pollutants in the environment that have the potential to mimic estrogen, one such chemical, which is known to have weak estrogenic activity, is Bisphenol-A (BPA). Before we go any further I should probably address the question of what is BPA. BPA is a chemical that is mostly used in the manufacture of plastics, so if you’ve ever used or handled or cooked with something plastic, you’ve been exposed to BPA. But is it dangerous and does exposure to BPA have any relation to endometriosis?

The trouble is it’s very difficult to measure the exposure of unborn children to environmental factors without putting the foetus at risk and I very much doubt pregnant women would be happy about being injected with a potentially harmful substance. One way around this is to perform experiments on animals, which is what one research team in Italy have done.

This study took pregnant mice and gave them, throughout their pregnancy, BPA in various doses. After the mice gave birth the pups were kept for 3 months then their ovaries were analysed to see what effect the BPA had. The results showed that mice exposed to BPA in the womb were more likely to develop damage to their ovaries. Not only that but some mice developed an endometriosis like condition.

That pretty worrying, right? Well let’s look a bit closer before we go off and start building our subterranean vacuum chamber. One of the issues with this study is the dose of BPA given; the mice in question received doses of BPA ranging from 100 to 1000 micrograms per kilogram per day. Although it sounds small, this is in fact a huge dose, likely exceeding anything any human would ever be exposed to. It’s a bit like trying to test the effect of microwaves on a potato by dropping a nuclear bomb on a farm (ok I’m exaggerating a bit there).

Then we have the age old problem of using mice as an analogue for humans. Whilst mice are surprisingly similar to humans, in a physiological respect, there are of course major differences, particularly in the reproductive systems. But there is also the difference in metabolism to take into consideration. Humans and mice metabolise BPA in different ways and this is important when considering the effect BPA has on the body. A study conducted at the Institute for Toxicology, Wurzburg University, Germany, found that humans metabolised and excreted BPA much quicker than rodents, meaning there is a much smaller chance of BPA having a harmful effect on the human body.

So is that the end of it? No need to worry about BPA? Maybe, but maybe not; there have been other studies showing that BPA levels are elevated in the blood of women with endometriosis, so perhaps women with endometriosis have a deficiency in the enzymes that metabolise BPA? Whilst that sounds like a fascinating hypothesis, otherstudies have shown that not to be the case and furthermore, there is no difference in the levels of urinary BPA between infertile women with endo and healthy controls, oh well so much for that idea. However, there is still no evidence concerning the effect of foetal exposure to BPA in humans and how this might relate to endometriosis risk. There have been other studies suggesting foetal BPA exposure affects childhood behaviour and brain function, however there are those that say no such association exists, so it is really difficult to come to any real conclusion here, the jury is still out on BPA.

As usual I would always encourage you to do your own research if you’re concerned about any topic, but be cautious when searching out there on the vastness of the internet. There are plenty of reactionary idiots with agendas to push and no evidence to back up their claims, a good rule of thumb I have is; if it sounds sensationalist, it’s probably not true.

3 comments:

Right, interesting, I have always said we need to look at the impact of these things on the fetal host, the mother, and how her exposures influence fetal cellular differentiation and migrationThanks for all you do

BpA, rBST, rBGH, synthetic estrogen is being used in most everything, down to the receipts you touch at every store, except when posted that there is no BPA in their receipts, but FYI, keeping us sick is good for business, true reports from the FDA have been blocked from coming out because of deep ties and money from Monsanto and Pharmaceuticals... It does mess with your natural estrogen, any foreign synthetic estrogen absorbed in the body does, even Birth control pills are a sign of this, used to mimic estrogen instead of just prescribing actual estrogen or progesterone, because they all make more Money--- BPA, and most of these chemicals are actually only legal in the US and third world countries!!!! Research it for yourself.... Most countries stopped importing our beef and dairy because rBST is outlawed due to significant studies showing damage to humans!!...

I took your advice hempheros and did some of my own research, although what I found doesn’t really tally with what you were claiming. For instance you said BPA is only legal in the US and the third world, this is untrue, BPA is widely used and legal in many countries and continents such as: The European Union, Australia, Canada, South America, China and Japan. You also claim that most countries have stopped importing US beef. Well I checked the US Meat Export Federation (USMEF) statistics and found US beef exports have been steadily increasing for over 6 years, in fact last year saw a 22% growth in beef export by the US, so clearly most countries have not stopped imports.

I'm not sure you have a full grasp of the pharmacodynamics of the oral contraceptive pill either. The function of the pill is to reduce the levels of estrogen in the body to a steady state, thus not allowing ovulation to take place and atrophying the proliferation of the endometrium. A small amount of synthetic estrogen is added to prevent side effects of estrogen deficiency. Synthetic estrogen (in this case ethinyl estradiol) must be used because endogenous estrogen, when taken orally, is rapidly broken down in the liver so would have little therapeutic value.

I’m also very interested in the significant studies you mentioned, are they meta-analyses, such as those published by Cochrane Reviews, or large cohort based studies published independently? Either way it would be great if you could post links to the Journals where these studies were published so I could have a look at the data and statistical analysis myself.

On a positive note though, several countries in the EU have now banned BPA in the manufacture of plastic baby bottles, which is encouraging considering the true physiological effects of endocrine disrupters are unknown, especially in the early developmental stages. I also read a report that some food manufacturers are looking into, and implementing, alternatives to BPA based packaging, so that’s also good news.

Endometriosis Update

Endometriosis is an enigmatic disease, little is known about its origins, but it affects the lives of millions of women around the world. Despite the apparent lack of advancement in the field of endometriosis research, progress is slowly being made. The problem is that this progress is very rarely reported accurately to the public in a way everyone can understand. This Blog aims to report what is going on in the area of endometriosis research in plain and simple terms, so that everyone can keep up to date. Updates will be pretty sporadic but I'll try to report items of interest as often as possible.